Currently, many color images are produced for various medical purposes using either single chip color video cameras or color cameras with 3 charge-coupled devices (CCDs), each of the CCDs being monochromatic and representing one of the primary colors R (red), G (green), and B (blue). The method of use of a single chip color camera is limited in resolution, since each pixel is dedicated to only one of the colors. The resolution obtained, therefore, would be significant lower.
Three-chip CCD cameras may be used for the production of monochrome as well as color images. However, prices for such a camera are significantly high, thus precluding the production of images with resolutions above 512.times.512 pixels.
In order to maximize resolution, a different method is used in which an illuminating means sequentially irradiates light of the three primary colors to illuminate the eye. The imaging signals are read in synchronism with the TV camera frame integration cycle for each color and are processed by a computer to display the image in color. This sequential color imaging has the advantage that it produces an image with high resolution, using a relatively inexpensive monochromatic single chip camera.
However, some procedures (e.g. fundus examination with indocyanine green (ICG)) require stronger light than that provided by a conventional light source, such as a non-coherent light. Prior art devices use flash pulse photography to get single frame photographs of the image desired. This often results in low-resolution images when an inadequate intensity of pulse is applied. Also, there are many cases where dynamic imaging is necessary and cannot be obtained with flash pulse photography.
A laser light could provide a continuous light source, however, the light intensity of a laser is undesirable for some uses because of its strength and the heat which it generates which raise safety issues regarding direct application to the eye. Therefore, it is necessary to decollimate the laser light. An infrared fundus video angiography system is provided in U.S. Pat. No. 5,400,791 to Schlier et al. having a decollimated laser light, however no monitoring is provided for ascertaining the safety of the light intensity passing through the system.
Thus, it would be desirable to provide a cost-efficient illumination system for high resolution monochrome or color-imaging in optical diagnostic equipment, integrating both conventional incandescent and laser light sources, both sources being monitored by a computer feedback system for precise and safe operation for a variety of uses.